The invention relates generally to coupling of RF signals, in particular to a device for coupling broadband RF signals for transmission through power lines and a method for installing same.
In the past, the only information service provided to customers such as businesses or private households was a telephone line. With technological advances more and more information services are provided to customers such as cable television, alarm connection, high speed Internet connection and so forth. In order to provide all these information services to customers each service provider has to run a dedicated cable to the premises of their customers. Each dedicated line is proprietary to the service provider and, therefore, has to be maintained by that service provider.
A significant expense in providing service to subscribers, is the physical link to the subscribers. Cable lines are often cut during gardening and other digging activities. Also, animals can break connections. There is a substantial expense in laying the original cables to the premise of each customer. Furthermore, an increasing number of different information services received by a customer require the installation of a plurality of physical links to the premise of a single customer.
In order to overcome these difficulties, it has been proposed to use a wireless communication system to provide all services. Unfortunately, this is generally costly and presents a plurality of drawbacks. Therefore, it is slow to gain wide acceptance and is even suffering difficulties in finding test areas.
One form of service that is provided in industrial nations to every household is electrical power. In areas serviced by a power company, an electrical connection to each household allows for power delivery. Further, the power lines are monitored regularly and are pole mounted or buried deep underground for safety.
For a power line to serve as a communications link transmitting high-speed data a device is needed for reliably coupling the high-speed data to the power line. In addition such a device has to be inexpensive, essentially maintenance free and easy to install in existing installations at a customer""s premise with minimum interruption or without interruption of the power supply to other neighboring premises in order to compete with contending technologies. Furthermore, such a device has to guarantee safety by isolating the communications function from the power supply function at the customer""s premise.
Several devices for coupling communications signals to a power line have been proposed in the following references, which are hereby incorporated by reference:
U.S. Pat. No. 4,142,178 issued Feb. 27, 1979 to Whyte et al.;
U.S. Pat. No. 5,864,284 issued Jan. 26, 1999 to Sanderson; and,
U.S. Pat. No. 6,040,759 issued Mar. 21, 2000 to Sanderson.
All these proposed devices are very complex in their structure requiring maintenance and are expensive to manufacture. Furthermore, these devices are difficult to install requiring disconnecting supply to the power line prior to the installation. Thus, these devices defeat their purpose for providing an inexpensive communications link to a customer""s premise that is easily installed.
It is, therefore, an object of the invention to overcome the drawbacks of the prior art and to provide a device for coupling RF broadband data signals to a power line that is inexpensive, and essentially maintenance free.
It is another object of the invention to provide a device for coupling RF broadband data signals to a power line that can be installed at a customer""s premise without disconnecting power to the power line.
It is further an object of the invention to provide a method for installing a device for coupling RF broadband data signals to a power line without disconnecting power to the power line during installation.
In order to overcome these and other limitations of the prior art, there is provided in accordance with the invention a coupling device for injecting and extracting a RF broadband data signal to and from a power line. The coupling device is inexpensive to manufacture, essentially maintenance free, and easy to install. In a preferred embodiment such a coupling device is installable absent a step of disconnecting power to the power line which provides power to a customer""s premise. Therefore, power supply to neighboring premises served by the same power line is not interrupted during installation.
In accordance with the invention there is provided a coupling device for providing a communications link for RF broadband data signals to a power line comprising:
a first port for connection to a power line;
a high-pass filter element connected to the first port, the filter element allowing RF broadband data signals to pass while substantially attenuating low frequency signals; and,
a second port connected to the high-pass filter element for connection to a RF broadband data signal line.
In accordance with the invention there is further provided a coupling device for providing a communications link for RF broadband data signals to a power line comprising:
a first port for connection to a power line;
a high-pass filter element connected to the first port, the filter element allowing RF broadband data signals to pass while substantially attenuating low frequency signals, wherein the high-pass filter element is connected to the first port via a cable having shielding spaced from the core at a sufficient distance to effectively limit noise resulting from the cable shielding in order to permit extraction of a RF broadband signal absent substantial noise; and,
a second port connected to the high-pass filter element for connection to a RF broadband data signal line.
In accordance with the invention there is further provided a coupling device for providing a communications link for RF broadband data signals to a power line comprising:
a first port for connection to a power line;
a high-pass filter element connected to the first port, the filter element allowing RF broadband data signals to pass while substantially attenuating low frequency signals;
a second port connected to the high-pass filter element for connection to a RF broadband data signal line;
a drain coil connected to the high-pass filter element and connected to ground, the drain coil providing grounding for low frequency signals but preventing the RF broadband data signals from being grounded; and,
a protective device connected in parallel to the drain coil for protecting the second port and the drain coil.
According to an aspect of the invention there is provided a coupling device for providing a communications link for RF broadband data signals to a power line comprising:
a first port for connection to a power line;
a second port for connection to a power input line of a premise and electrically connected to the first port via a power passthrough for providing power to the premise, wherein the power passthrough comprises a cable having shielding spaced from the core at a sufficient distance to prevent substantial noise from occurring within the RF broadband data signal;
a high-pass filter element connected to the power passthrough, the filter element allowing RF broadband data signals to pass while substantially attenuating low frequency signals;
a third port connected to the high-pass filter element for connection to a RF broadband data signal line;
a ground terminal for connection to ground;
a drain coil connected to the high-pass filter element and connected to the ground terminal, the drain coil providing grounding for low frequency signals but preventing the RF broadband data signals from being grounded; and,
a protective device connected in parallel to the drain coil for protecting the third port and the drain coil.
According to another aspect of the invention there is provided a method for installing a coupling device for providing a communications link for RF broadband data signals to a power line while the power line is provided with a power signal, the method comprising the steps of:
first connecting a ground terminal of the coupling device to a ground terminal connected to a ground and connecting a port of the coupling device for connection to a RF broadband data signal line to a same;
second connecting a port of the coupling device for connection to a power input line of a premise to a same; and,
third connecting a port of the coupling device for connection to a power line to the power line comprising a power signal.